linux-kernel - RE: [PATCH 2/3] rtc: imx-sc: Make compatible string more generic

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Message-ID: <DB3PR0402MB3916A7887EBC63477A5297E6F5EC0@DB3PR0402MB3916.eurprd04.prod.outlook.com>
Date:   Wed, 12 Jun 2019 00:48:27 +0000
From:   Anson Huang <anson.huang@....com>
To:     Trent Piepho <tpiepho@...inj.com>,
        "festevam@...il.com" <festevam@...il.com>
CC:     Aisheng Dong <aisheng.dong@....com>,
        "alexandre.belloni@...tlin.com" <alexandre.belloni@...tlin.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        dl-linux-imx <linux-imx@....com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "a.zummo@...ertech.it" <a.zummo@...ertech.it>,
        "mark.rutland@....com" <mark.rutland@....com>,
        Peng Fan <peng.fan@....com>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Daniel Baluta <daniel.baluta@....com>,
        "ulf.hansson@...aro.org" <ulf.hansson@...aro.org>,
        "kernel@...gutronix.de" <kernel@...gutronix.de>,
        "linux-rtc@...r.kernel.org" <linux-rtc@...r.kernel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>
Subject: RE: [PATCH 2/3] rtc: imx-sc: Make compatible string more generic

Hi, Fabio/Trent

> -----Original Message-----
> From: Trent Piepho <tpiepho@...inj.com>
> Sent: Wednesday, June 12, 2019 4:46 AM
> To: festevam@...il.com; Anson Huang <anson.huang@....com>
> Cc: Aisheng Dong <aisheng.dong@....com>; alexandre.belloni@...tlin.com;
> robh+dt@...nel.org; dl-linux-imx <linux-imx@....com>; linux-
> kernel@...r.kernel.org; devicetree@...r.kernel.org;
> a.zummo@...ertech.it; mark.rutland@....com; Peng Fan
> <peng.fan@....com>; shawnguo@...nel.org; linux-arm-
> kernel@...ts.infradead.org; Daniel Baluta <daniel.baluta@....com>;
> ulf.hansson@...aro.org; kernel@...gutronix.de; linux-rtc@...r.kernel.org;
> s.hauer@...gutronix.de
> Subject: Re: [PATCH 2/3] rtc: imx-sc: Make compatible string more generic
> 
> On Tue, 2019-06-11 at 17:32 -0300, Fabio Estevam wrote:
> > Hi Anson,
> >
> > On Tue, Jun 11, 2019 at 3:31 AM <Anson.Huang@....com> wrote:
> > >
> > > From: Anson Huang <Anson.Huang@....com>
> > >
> > > i.MX system controller RTC driver can support all i.MX SoCs with
> > > system controller inside, this patch makes the compatible string
> > > more generic to support other i.MX SoCs with system controller
> > > inside, such as i.MX8QM etc..
> > >
> > > Signed-off-by: Anson Huang <Anson.Huang@....com>
> > > ---
> > >  drivers/rtc/rtc-imx-sc.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/rtc/rtc-imx-sc.c b/drivers/rtc/rtc-imx-sc.c
> > > index c933045..38ef3ca 100644
> > > --- a/drivers/rtc/rtc-imx-sc.c
> > > +++ b/drivers/rtc/rtc-imx-sc.c
> > > @@ -178,7 +178,7 @@ static int imx_sc_rtc_probe(struct
> > > platform_device *pdev)  }
> > >
> > >  static const struct of_device_id imx_sc_dt_ids[] = {
> > > -       { .compatible = "fsl,imx8qxp-sc-rtc", },
> > > +       { .compatible = "fsl,imx-sc-rtc", },
> >
> > What is wrong with the current compatible string?

Nothing wrong, just want to make it aligned with other SCU drivers, like
SCU watchdog, SCU thermal etc., the driver ONLY contains "fsl,imx-sc-xxx"
compatible string, then for new SoC, we can just add it as compatible or
fallback compatible string, no need to do any change for driver.  

> >
> > If you want to support i.MX8QM just add in its dtsi:
> >
> > compatible = "fsl,imx8qm-sc-rtc", "fsl,imx8qxp-sc-rtc"
> >
> > and add a dt-bindings entry for "fsl,imx8qm-sc-rtc"

I am OK if we can just use " fsl,imx8qxp-sc-rtc" as fallback compatible string
for later SoCs.

> 
> Yes, I thought this is (was?) the recommended practice for IP blocks in SoCs
> that don't have their own version (vs something like a Synopsis block used
> many places):
> 
> * Use the first SoC to have the block as the base compatible for the block.
> * Always add the current SoC, in additional to the base, in the SoC's dts's list
> of compatibles.  Even if unneeded at the present.
> * The driver will list the base compatible in the match table, and will add new
> ones for specific socs if/when there is a need for it.

Make sense, I was recommended to make the fallback compatible string aligned
for all SCU drivers, for me, I am OK with either way, so if you think it is NOT necessary
to do it, we can drop this series.

Thanks,
Anson